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Originally posted by badrinathn Under what circumstances does one need to dump the undo header information?

When one is extremely bored and has no better things to do!

No seriously, there are some information in undo headers that are sometimes interesting to analyze. In particularly the transaction table stored in undo header might give you interesting information about what is going on in a particular moment of time in a particular rollback segment.

Jurij ModicASCII a stupid question, get a stupid ANSI
24 hours in a day .... 24 beer in a case .... coincidence?

Under what circumstances does one need to dump the undo header information?

Assume that you execute a huge transaction ( some thing like 20 M rows update) and later you decide to rollback. Rollback activity may take longer time what you expected. In that case, you dump the undo header block to see the progress of the rollback activity and time it needs to complete (do your math after going the block level details).

Originally posted by tamilselvan Under what circumstances does one need to dump the undo header information?

Assume that you execute a huge transaction ( some thing like 20 M rows update) and later you decide to rollback. Rollback activity may take longer time what you expected. In that case, you dump the undo header block to see the progress of the rollback activity and time it needs to complete (do your math after going the block level details).

You don't need to dump undo header for that. You can conclude this simply by monitoring the V$TRANSACTION.USED_UBLK decreasing rate. However if the rollback of the transaction is part of the instance recovery, then you indeed need to dump the RBS header to estimate the duration of the transaction rollback - which BTW should not be of so much interest in recent releases of Oracle with delayed transactions crash recovery feature.